Poultry Production in Nigeria

Poultry are domesticated birds kept by humans for eggs they produce, their meat, feathers or sometimes as pets. They were domesticated several years ago when having a captive-bred source of food was realized as useful (West and Zhou, 1988). These birds are most typically members of the super order Galloan serae (fowl) especially the order Galliformes which includes chickens, guinea fowls, quails and turkeys.

The word “Poultry” comes from a French/Norman word “Poule” itself derived from the Latin word “Pullus” which means small animal, young fowl or chicken. Poultry is the second most widely eaten type of meat globally providing nutritionally beneficial food containing higher quality protein accompanied by a low proportion of fat (Garrigus, 2007).
One of the most common and wide spread poultry is chicken. The scientific name is Gallus domesticus. Locally it’s called “Okuko” in Igbo, “Adere” in Yoruba, “Kasa” in Hausa and “Okhokho” in Benin. Chickens are gregarious birds and live together as a flock. They are medium sized chunky birds with an upright stance and characterized by fleshy red combs and wattles on their heads.

The males are the cocks, females are hens and the younger ones are the chicks (Crawford, 1990). The males are usually larger, more bodily coloured and have more exaggerated plumage than females. Chickens are omnivorous ground-dwelling birds that in their own natural environment search among the leaf litters for seeds, invertebrates and other small animals. They seldom fly except as a result of perceived danger but they are not capable of long distance flight just short distance such as over fences (Sherwin and Nicol, 1993).

Chicken meat also called chicken is a major source of protein. It contains about 2 to 3 times as much polyunsaturated fat as most types of red meat when measured by weight. It also contains cancer-protective vitamin B, niacin. A risk is present for consumers of poultry meat to bacterial infections caused by organisms like Campylobacter, Staphylococcus aureus, Salmonella and so on. This contamination by these bacteria on poultry meat occurs during handling, processing, marketing, or storage which may result to food borne illnesses. Thorough cooking of poultry meat would kill bacteria so proper cooking and handling is advised (Webster, 2003).

Aim and Objectives
The aim of the study is to isolate and identify microorganisms associated with poultry meat.

Objectives
• To determine the level of contamination or occurrences of the organisms.
• To give recommendations to improve safety of poultry meat.

Literature Review
The domestication of poultry as believed took place several thousand years ago. This may have originally been as a result of people hatching and rearing young birds from eggs collected from the wild, but later got involved with keeping the birds permanently in captivity (West and Zhou, 1988). Domesticated chickens may have been used for cockfighting, the male being a doughty fighter and the quails kept for their songs at first. The Romans used chickens in divination. In Egypt they were used for fighting and were regarded as symbol of fertility. Soon it was realized how useful it was having a captive-bred source of food.

Selective breeding for fast growth, egg-laying ability, conformation, plumage and docility took place over the centuries. Since then the keeping of chickens has spread around the world for the production of food (Al-Nasser, 2001).
Poultry meat is the second most widely eaten type of meat in the world accounting for about 30% of total meat production worldwide compared to pork at 38%. Poultry meat provides nutritionally beneficial food containing high quality protein accompanied by a low proportion of fat (Martinez, 2013). Chicken as its most common source is usually subject to intensive farming methods. The different kinds are capons, pullets and hens. The capons which are the castrated cocks produce more and fatter meats. Chickens raised specifically for food are called broilers. The meatiest parts are the flight muscles on its chest called breast meat, the walking muscles on the legs called the thigh and drumsticks.

The wings are also eaten and may be split into 3 segments, the meatier “drumette”, the flat “wingette”, and the “flapper” which is the wing tip. Chicken is available frozen or fresh. Fresh chicken just as other meats contains an abundance of all nutrients required for the growth of microorganisms. They are sensitive to contamination and support growth of microorganisms involved in spoilage and food borne illnesses. Proper handling and cooking is advised (Manning et al., 2007).

Biology and Habitat Of Poultry Chicken
The chicken is an interesting creature when observed from a biological stand point (Crawford, 1990). It has a high rate of metabolism, is a rapid breather and digests its food relatively quickly. The body temperature varies but averages around 106 degrees F. The comb functions as its cooling system. The feathers cover most of its body but grow from defined areas called feather tracts. The chicken has hollow bones (bones of the skull, humerus, clavicle, lumbar and sacral vertebrae) and medullary bones (tibia, femur, pubic bones, sternum, ribs, ulna, toes and scapula). Chickens depend on enzymes to aid in breaking down food so it can be absorbed much like humans and its beak replaces the mouth and lips (Webster, 2003). The crop is a pouch formed to serve as a storage area for the food until it can be passed along for digestion in the gizzard and intestine. The gizzard is an oval organ with two pairs of thick red strong muscles used to grind/crush the food particles. The proventriculus is the true stoach form which hydrochloric acid and pepsin is secreted to aid in digestion. Digestion and absorption takes place in the small intestine and it takes about two and half hours for food to pass through the digestive tract from beak to cloaca (Sherwin et al., 2010).

Domestic chickens have no natural habitat. However, the best place to keep them is a grassy area that offers a greater diversity of plants and insects. They should be kept near a home for proper supervision with a nearby water source since they take lots of water. In creating habitat, a small flock size is better than large to create more space. Their house should be well ventilated to allow easy flow of air, have proper sanitation with no stagnant water or wet environment to avoid bacteria breeding space or other dangerous organisms which could infect the chickens. In case some get sick, they are isolated from the healthy ones and treated (Crawford, 1990).
Poultry Diseases
These are diseases of poultry caused by microorganisms which could be bacteria, virus, fungi or parasites. Some of which can spread from poultry to humans if eaten.

Generally these diseases can be controlled by proper hygiene, isolation of sick ones, treatment of sick chickens and also keeping records of daily activities and observations (Manning et al., 2007).

Processing of Poultry Meat
Meat is an edible animal flesh which comprises principally the muscular tissue, and also includes internal organ called viscera such as heart, liver, kidney, intestine and bladder (Adams and Moss, 1999). (Okala and Reedi, 2001) relate that the bulk of meat is derived from goat, cattle, pig, sheep, and poultry. Meanwhile the processing of meat products includes those prepared product for consumption, increases the quality, texture, flavour, colour as well as reduce bacterial contaminant of meat used (James, 2001). Poultry processing is the preparation of meat from various types of fowls for human consumption. Humans consume poultry in different ways varying by regions and culture, it could be fried, baked, grilled or roasted so it’s essential that poultry meat quality and safety are maintained during production and processing. Poultry meat processing begins by establishing consumer requirements for meat quality before examining the influence of breeding/husbandry and techniques for stunning and slaughter of poultry (Martinez, 2013).

Chickens are taken directly from the growing farms to the processing plant where they are unloaded from transport crates, slaughtered, plucked, cleaned, cooled and graded. They are then either packaged and frozen or chilled and could be processed further into various products prior to packaging and sale to distributors. According to (Ikeme, 1990) the chemical composition of meat varies considerably with age, species, degree of fatness of animal, the part of carcass involved etc. In poultry meat microorganisms multiply rapidly especially at non- refrigeration temperature resulting in loss of quality and public health problems. Thus various methods of processing and preservation are being applied to inactivate or inhibit microbial growth in order to extend product shelf-life while maintaining palatability and safety (Manning et al., 2007).
A study in a chicken processing plant noted that contamination of carcasses with Listeria spp occurred through contaminated surfaces and equipments (Hudson and Mead, 1989). It is also important to note that Listeria spp is capable of multiplying at refrigeration temperatures (Walker et al., 1990). All significant poultry processing operations are to have a systematic preventive approach to managing food safety risks with approved and regularly audited Hazard analysis and critical control points (HACCP) programs in place.

Spoilage of Poultry Meat
About 80% of poultry are marketed as fresh product. It’s estimated that 2% to 4% of this meat is lost as a result of spoilage. Therefore spoilage is of great concern to the poultry industry. The primary causes of spoilage on poultry meat are:
• Prolonged distribution or storage time.
• Inappropriate storage temperature.
• High initial bacterial count.
• High post-rigor meat pH.

Spoilage of meat occurs if the meat is untreated which results in the meat becoming unappetizing, poisonous or infectious. Spoilage is caused by the subsequent decomposition of meat by organisms such as bacteria which are borne by the chicken itself, the handlers, or by the processing equipments. The organisms spoiling poultry meat may infect chickens either while still alive (endogenous) or after it’s slaughter (exogenous). These micro-organisms are Bacillus spp, Clostridium spp, Escherichia coli, Salmonella spp, Shigella spp, Staphylococcus aureus, Streptococcus pyogenes, Proteus, Pseudomonas, Leuconostoc, Lactobacillus sp, Micrococcus, Mycobacterium sp, Vibrio sp etc (Baird-Parker, 1993). Salmonella may be transferred from raw meat to cooked meat by hands, surfaces or utensils (Jay, 2000). The presence of food borne pathogens in meat and meat products can result in a range of human health problems as well as economic losses to producers due to recalls from market places (Sofos, 2008). Extrinsic factors such as temperature, relative humidity, oxygen availability and other factors including chemical and physical properties of meat affect microbial growth (Adams and Moss, 1999). Additionally, some species of bacteria such as Listeria monocytogenes are capable of surviving anaerobic conditions, which can lead to greater threats to the integrity of these products (Buchanan and Klawitter, 2006).

The principle spoilage organisms are bacteria like Staphylococcus aureus, Staphylococcus epidermis, Escherichia coli, Salmonella spp, Shigella spp, faecal Streptococci, Listeria spp and molds like Penicillium notatum. The organisms are responsible for detrimental quality changes in poultry meat which includes discoloration, unpleasant odours and physical alterations. Some of these organisms, such as Listeria spp can be present in raw meat, which may serve as a source for cross-contamination of finished products (Samelis and Metaxopoulos, 1999). Salmonella spp is also present on raw chicken-based meats, a finding in agreement with previous studies on poultry, which have asserted this meat as a carrier of this pathogen (Guard-Petter, 2002) (Xiong et al., 1998). Contamination of processed foods can also occur due to poor quality water and unacceptable levels of airborne microorganisms in the processing environment (Kirby et al., 2003). Furthermore, temperature and humidity in the food processing environment play an integral role in the quality of products manufactured (Lee-Wong, 1998).

The use of low ambient temperatures during production diminishes the ability of microorganisms to grow and replicate. A study conducted in the USA showed that among four meat processing plants, the one with the lowest temperature (7-18 degrees Celsius) had the lowest counts of airborne bacteria (Lutgring, 1997). The effect of warm temperatures on microbial load of food processing environments was also documented in a poultry processing plant in the US where bacterial counts were higher during warmer summer months when compared to winter months (Lutgring, 1997). However, lowering temperature can also result in increasing relative humidity, and both of these factors are known to favor the development of bacterial growth (Else et al., 2003). Infected meat however should be eliminated through systematic inspection in production, use of properly cleaned slaughter or dressing implements (Barnes and Thornley, 1966). Several microbiological guidelines for processed foods have been established by agencies, including the World Health Organization (WHO) and the National agency for Food and Drug Administration and Control (NAFDAC). These guidelines are commonly used for developing food safety programs such as Hazard Analysis and Critical Control Points (HACCP), Good Manufacturing Practices (GMPs) and Good Hygienic Practices (GHPs) (Lammerding, 1997). Hence the isolation and identification of bacteria present in meat and its product is necessary to anticipate the extent of spoilage under storage and handling procedures (Luyet, 2000).